Use of cooling system to heat air supply

ABSTRACT

A method for conditioning air, the method comprising flowing a first air flow within a first ventilation system past a first cooling coil, which is connected to a cooling system with a cooling fluid and a cooler, characterised in that the temperature of the first air flow, when passing the first cooling coil, is lower than the temperature of the cooling fluid flowing through the first cooling coil and that the first air flow is heated and the cooling fluid flowing through the first cooling coil is cooled, when the first air flow passes through the first cooling coil.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is U.S. National Phase of International PatentApplication Serial No. PCT/EP2018/082920 entitled “METHOD FORCONDITIONING AIR,” filed on Nov. 29, 2018. International PatentApplication Serial No. PCT/EP2018/082920 claims priority to EuropeanPatent Application No. 17204317.6 filed on Nov. 29, 2017. The entirecontents of each of the above-referenced applications are herebyincorporated by reference for all purposes.

TECHNICAL FIELD

The invention relates to a method for conditioning air, the methodcomprises flowing a first air flow within a first ventilation systempast a first cooling coil, which is connected to a cooling system with acooling fluid and a cooler. Furthermore, it relates to a device forconducting the method according to the invention.

BACKGROUND AND SUMMARY

Conventionally, air conditioning systems, in particular air handlingunits (AHU) or heating, ventilation and air condition (HVAC) systems,use a cooling system including a cooler and a cooling coil to cool anair flow and a heating system including a heater and a heating coil toheat an air flow. A variety of such systems are known that are supposedto reduce the amount of energy that has to be put into heating and/orcooling.

For example, US 2013/0213608 A1 shows a device, wherein outside air iscooled and dehumidified by a cooling system. A part of the cooling fluidof the cooling system, which has a higher temperature after the processof cooling the air, is led back to a heating system. For this purpose,the cooling coil has an outlet for putting out the fluid and the heatingcoil has an inlet for receiving the fluid. The heating system heats thecooled/dehumidified air, before the air is given off in an indoor space.By use of the heat given off of the cooling fluid that was led back, theheating power of the heating system can be reduced, such that power canbe saved.

However, all these need to be constructed in a specialised way orexisting systems have to be upgraded, in order to be applicable. Thus,one problem to be solved by the present invention is to provide an easymethod for saving energy in an air conditioning system. Another problemis to be able to save energy using existing systems or only having toapply minimal changes to existing systems. Furthermore, it should alsobe possible by the method and device of the present invention to providean easy measure for saving energy in air conditioning systems that getnewly constructed. Furthermore, preferably, less resources should beused in constructing such an air conditioning system.

This is solved by the temperature of the first air flow, when passingthe cooling coil, being lower than the temperature of the cooling fluidflowing through the first cooling coil and that the first air flow isheated and the cooling fluid flowing through the cooling coil is cooled,when the first air flow passes through the first cooling coil.Furthermore, it is solved by a device comprising a control device forconducting the method according to the invention.

By this way, an air conditioning system can use the cooling system toheat air. Furthermore, the system can save energy, because the heat inthe cooling system is already available and does not need to beproduced. Additionally, the cooling fluid gets cooled in this process,so the temperature of the cooling fluid is lowered without the need toconsume energy to cool the cooling fluid. Depending on how much thecooling fluid needs to be cooled for other applications, the cooler canrun in a full power mode, in a reduced power mode, or be switched off.

Preferably, the method further comprises drawing in outside air, furtherpreferably through an air intake damper, into the first ventilationsystem such that the outside air makes up the first air flow.Furthermore, one can set a temperature set point, which defines thetemperature to which the outside air, or generally the air flow in thefirst ventilation system, should be heated. The method of the presentinvention is particularly applicable, when the temperature set point andthe temperature of the cooling fluid flowing through the first coolingcoil are higher than the temperature of the outside air. Since thetemperature set point is higher than the outside temperature and sincethe temperature of the cooling fluid flowing through the first coolingcoil is higher than the outside temperature, it is possible to heat thefirst air flow, using the cooling system and the cooling coil, beingequivalent to the outside air being drawn in. In a preferred variant ofthe method, this air is then heated by a heating coil. This pre-heatingof the air may be sufficient to meet the temperature supply set point ofthe first ventilation system, especially when the first ventilationsystem is supplying areas that need cooling, or a mixture of heating andcooling or different heating supply temperatures. Areas that needadditional heat can either be served with top-up heat from a localsecond heating system and/or, a re-heating coil (where provided) in thefirst ventilation system can be engaged to provide top-up heat to thefirst air flow after it has been preheated by passing through the firstcooling coil. Usually the temperature set point for preheating the airwill be between 12 degrees Celsius and 19 degrees Celsius. Thus thetemperature set point guarantees the comfort of people who are affectedby the air conditioning system, because the heating system continues tobe capable of providing any necessary top-up heat to meet the spacetemperature set point requirements in a preferred embodiment. This alsoapplies to process air supply systems where the air is primarilyconditioned for purposes other than human comfort. Additionally, if theoutside air temperature is low, the cooling system can operate at anelevated temperature.

In a preferred variant of the method, it further comprises heating thefirst air flow by flowing the first air flow past a first heating coil,before flowing the first air flow past the first cooling coil, and/orfurther heating the first air flow by flowing the first air flow past asecond heating coil, after flowing the air flow past the first coolingcoil, wherein the first and the second heating coil are connected to aheating system with a heater. By this use of at least one additionalheating coil, the temperature of the first air flow can be furtherelevated than would be possible by using the cooling system alone. Thesystem can also only comprise one of the heating coils or make use ofonly one of the heating coils, or comprise more than two heating coilswith a variety of possible arrangements. The system can of course alsocomprise more than one cooling coil, placed in different positionsrelative to the first cooling coil and the heating coils. Furthermore,the first heating coil can be a preheating coil and can protect thecooling coil from frost, depending on the temperature of the first airflow and in particular of the outside air being drawn in. The secondheating coil can in particular be a reheat coil, such that the systemcan be used for dehumidifying the air, under conditions when the presentinvention might not be applicable, by cooling the air flow in thecooling coil, and reheating it in the reheating coil. Thus, the methodis applicable to normal air conditioning systems already in use, whichcan be used for providing heated, cooled, humidified (where a humidifieris provided) and/or dehumidified air.

Since not only the heating coils, but also the cooling coil is used forheating in the method of the present invention, it is possible that theheater is running at a lower temperature, i.e. consuming less energy,that the flow in the heating system is lower and/or that the area of thecoils is lower or the coils are smaller than would have been requiredwithout this method. Additionally, under certain conditions it may bepossible to switch off the heater. Furthermore, under certainconditions, it may be possible to avoid the need for a pre-heating coiland instead use the cooling coil for pre-heating/heating.

Preferably, in the method, one uses for the cooling coil a coil that hasmore rows/fins than one or all of the heating coils. This allows for theuse of only one cooling coil or fewer cooling coils than heating coilsand for a lower temperature difference between the cooling fluid and thefirst air flow. Furthermore, the cooling coil preferably uses a draintray, such that when it is used for dehumidifying the air, the draintray collects the condensed water.

Preferably, the method further comprises using the residual heat of thecooling fluid in the cooling system to heat the first air flow. By thisway one does not need to provide any additional energy to heat the firstair flow, thus saving energy normally used by the air conditioningsystem. Preferably in such a variant, the cooler is turned off, as tonot reduce the amount of residual heat available. It is clear that thismethod can only be used for a limited amount of time if no additionalenergy is brought into the cooling system, since the residual heat willbe used up eventually, or the temperature difference might be too lowfor effective heat exchange.

In another preferred variant of the method, it further comprises asecond air flow in a second ventilation system with a second coolingcoil, wherein the second cooling coil is connected to the cooling systemand the cooling fluid is also flowed through the second cooling systemand the second cooling coil, wherein the cooling fluid is heated, whilebeing flown through the second cooling coil. Thus, there is a heat inputinto the cooling system, which can again be put out at the first coolingcoil, reducing the amount of heat that has to be provided by the heater.Conversely, the cooling fluid is cooled at the first cooling coil,reducing the amount of power required by the cooler in order to providecooling via the second cooling coil. Thus, there is an energy savingboth in the heater and the cooler, or in one of them.

In another preferred variant of the method, it further comprises asecond cooling emitter (e.g. a chilled beam), wherein the second coolingemitter is connected to the cooling system and the cooling fluid is alsoflowed through the second cooling emitter, wherein the cooling fluid isheated, while being flowed through the second cooling emitter. Thus,there is a heat input into the cooling system, which can again be putout at the first cooling coil, reducing the amount of heat that has tobe provided by the heater. Conversely, the cooling fluid is cooled atthe first cooling coil, reducing the amount of power required by thecooler in order to provide cooling via the second cooling emitter. Thus,there is an energy saving both in the heater and the cooler, or in oneof them.

Preferably, the method further comprises providing air conditioning fora facility. Even more preferred, it comprises blowing the first air flowfrom the first ventilation system, optionally with a supply air fan,into a first area of the facility, the second air flow is drawn into thesecond ventilation system from a second area of the facility, which canbe overlapping with the first area, and the second air flow is blownfrom the second ventilation system into a third area of the facility,which can be overlapping with the first and/or the second area. Thus,the air conditioning system can provide cooling to some area of thefacility, while it can also provide heating to some other area, whichcan also be overlapping with the area provided with cooling. These areascan also be changed according to where there is need for cooling and forheating.

It is preferable that the method further comprises measuring the outsidetemperature, the temperature of the first cooling fluid and/or thesecond cooling fluid and/or the ambient temperature in the first, secondand/or third area of the facility. This makes it easier to determine theexact parameters under which the method can be applied. Furthermore itis preferable to control the flow of the first air flow, even morepreferably by regulating the supply air fan and/or the air intakedamper, and/or of the second air flow, the flow of the cooling fluid,even more preferably by using and regulating a valve and/or a pump inthe cooling system, the flow of a heating fluid in the heating system,even more preferably by using and regulating a valve and/or a pump inthe heating system, and/or the power of the cooler and/or the heater.All these measures ease reaching the right temperature of each air flow,while reducing the energy consumed, or make it possible to use smallercoils, a less powerful heater and/or cooler and/or a lower flow rate inthe ventilation systems or the heating and/or cooling system.

Preferably, the method further comprises filtering the first air flow inthe first ventilation system, even more preferably by using panelfilters and/or bag filters. Thus, the air provided by the airconditioning system can have a higher quality. Furthermore, it ispreferable that the first air flow is also humidified in the firstventilation system. Since the method of the present invention isparticularly applicable when there is a low outside temperature,preferably a temperature of less than 15 degrees Celsius, even morepreferably of less than 10 degrees Celsius, the most preferably of lessthan 7 degrees Celsius, the relative humidity of the first air flow willbe reduced, when it is heated. Thus, it can provide a higher air qualityand a higher comfort for people potentially affected by the airconditioning system, if the first air flow is humidified.

In another variant of the invention, it can also comprise dehumidifyingthe first air flow.

Preferably, some or all of the preferred measures mentioned above forthe first ventilation system are also applied to the second ventilationsystem.

Furthermore the invention comprises a device for conditioning air,comprising a first ventilation system with a first air flow, preferablyconnected with the outside, the connection even more preferablycomprising an air intake damper, a first cooling coil, preferablycomprising a drain tray, in the first ventilation system, connected to acooling system with a cooler, preferably further comprising a valveand/or a pump in the cooling system, a heating system with a heater anda first and a second heating coil arranged in the first ventilationsystem, wherein even more preferably the first and the second heatingcoil have less rows and/or fins than the cooling coil and/or the heatingsystem comprises a valve and/or a pump, a second ventilation system witha second air flow and/or a second cooling emitter, within which a secondcooling coil/emitter is arranged that is connected to the same coolingsystem as connected to the first ventilation system, wherein a controldevice is provided for conducting a method as described above.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is schematic diagram of an example of an air conditioning system.

Hereafter, the invention will be described more closely on the basis ofa preferred embodiment depicted in the drawing FIG. 1. However, theinvention shall not be considered limited to this preferred embodiment.

DETAILED DESCRIPTION

In particular, FIG. 1 shows an air conditioning system 1 with a firstventilation system 2, a cooling system 3 and a heating system 4. Thefirst ventilation system 2 comprises an air intake damper 112, throughwhich outside air 101, e.g. 2 degrees Celsius, is drawn into the firstventilation system 2, wherein the outside air 101 has a temperature 102.The drawn in outside air 101 makes up the first air flow 5.Consequently, the first air flow 5 within the first ventilation system 2is filtered through a panel filter 113 and a bag filter 114.

Next, the first air flow 5 passes a first heating coil 106, which canalso be termed as a preheating coil, where the first air flow 5 isheated from the outside air temperature 102, e.g. 2 degrees Celsius, toa higher temperature, e.g. 5 degrees Celsius. If the outside airtemperature 102 is below freezing temperature, in particular belowfreezing temperature of a cooling fluid 6, then the temperature of thefirst air flow 5 should at least be elevated above the freezingtemperature by the first heating coil 106.

Thereupon, the first air flow 5 passes the first cooling coil 107. Thetemperature of the first air flow 5 immediately before the first coolingcoil 107 is lower than the temperature of the cooling fluid 6 flowingthrough the first cooling coil 107. Thus the first air flow 5 is heatedupon passing the first cooling coil 107, while the cooling fluid 6 iscooled. The elevated temperature of the first air flow 5 after passingthe cooling coil can for instance be 13 degrees of Celsius. Meanwhile,the temperature of the cooling fluid 6 immediately before flowingthrough the first cooling coil 107 can be 16 degrees Celsius, whichcorresponds to an elevated temperature, as normally possible forseasonally cooler periods of the year. After passing the first coolingcoil 107, the temperature of the cooling fluid can for example be 14degrees Celsius. Thus, the cooling fluid 6 has received “free” cooling,while the first air flow 5 has received “free” heating, where “free”means that no additional energy has been consumed in a heater or acooler.

Ensuingly, the first air flow 5 passes the second heating coil 108,wherein the temperature of the first air flow 5 is further elevated to afinal temperature 111, which can e.g. be 18 degrees Celsius. The secondheating coil 108 can also be termed a reheat coil, since underconditions to which this invention may not be applicable, it might beused for reheating the first air flow 5, after it had been cooled andthus dehumidified in the first cooling coil 107. Next the first air flow5 passes a humidifier 115, which can provide extra humidification incase this is required.

Lastly, the first air flow 5 is blown into a first area 103 of afacility at a final temperature 111 by a supply air fan 105.

The first cooling coil 107 is connected to the cooling system 3containing the cooling fluid 6. The cooling system further comprises apump 119, cooling control valve 121 and a cooler 109. The cooling systemcan further comprise a second cooling coil, connected to a secondventilation system (not depicted in FIG. 1) and/or second coolingemitter 123 (e.g. a chilled beam or fan coil). Depending on theconditions of the second ventilation system, the cooler 109 can berunning in a full power mode, a reduced power mode or be switched off.

The first and the second heating coil are connected to the heatingsystem 4, which further comprises a heater 110, pre-heating controlvalve 120, re-heating control valve 122 and pump 118. Exemplary, by useof the method of the current invention, the heating system 4 only has toheat the first air flow 5 from 2 to 5 degrees of Celsius and from 13 to18 degrees of Celsius, while without the use of the method of thepresent invention it would have to heat the first air flow 5 from 2 to18 degrees of Celsius.

A control device 7 is provided for controlling some or all of the HVACsystem components. By means of the control device 7 especially coolingsystem pump 119 is activated in case the temperature of the first airflow 5 immediately before the first cooling coil 107 is lower than thetemperature of the cooling fluid 6 flowing through the first coolingcoil 107.

The two charts below the schematic depiction of the air conditioningsystem are a temperature chart for the first air flow 5 on the top and atemperature chart for the cooling fluid 6 on the bottom. The doublepointed arrow in the first air flow temperature chart illustrates anexample of the heating energy that can be saved by implementing thepresent invention. The double pointed arrow in the cooling fluidtemperature chart depicts an example of the cooling that is achievablewithout additional energy expediture from the cooler 109 by implementingthe present invention. The values in the temperature chart follow theexemplary values mentioned above.

The preferred embodiment depicted in the FIGURE and described hereinshall only serve to explain the invention and shall in no way limit theinvention to this embodiment.

1. A method for conditioning air, the method comprising flowing a firstair flow within a first ventilation system with a first air intake, afirst output or air supply, and a first cooling coil therebetween,flowing the first air flow past the first cooling coil, which isconnected to a cooling system with a cooling fluid and a cooler capableof cooling the cooling fluid and delivering the cooled cooling fluid tothe cooling coil, wherein a temperature of the first air flow, whenpassing the first cooling coil, is lower than a temperature of thecooling fluid flowing through the first cooling coil and that the firstair flow is heated and the cooling fluid flowing through the firstcooling coil is cooled, when the first air flow passes through the firstcooling coil, wherein the residual heat of the cooling fluid in thecooling system is used to heat the first air flow.
 2. The methodaccording to claim 1, wherein the method comprises drawing in outsideair at a temperature, into the first ventilation system such that theoutside air makes up the first air flow, and prescribing a temperatureset point for the first ventilation system, wherein the temperature setpoint and the temperature of the cooling fluid flowing through the firstcooling coil are higher than the temperature of the outside air.
 3. Themethod according to claim 1, wherein the method further comprisesheating the first air flow by flowing the first air flow past a firstheating coil, before flowing the first air flow past the first coolingcoil, and further heating the first air flow by flowing the first airflow past a second heating coil, after flowing the first air flow pastthe first cooling coil, wherein the second heating coil is connected tothe heating system with the heater.
 4. The method according to claim 3,comprising using a coil with a drain tray as the first cooling coil. 5.The method according to claim 1, wherein the method comprises turningthe cooler off or reducing its output.
 6. The method according to claim1, wherein the method further comprises cooling a second air flow in asecond ventilation system with a second air intake, a second output orair supply, and a second cooling coil therebetween, wherein the secondcooling coil is connected to the cooling system and the cooling fluid isalso flowed through the second cooling coil, wherein the cooling fluidis heated while flowing through the second cooling coil.
 7. The methodaccording to claim 1, wherein the method further comprises cooling asecond cooling emitter, wherein the second cooling emitter is connectedto the cooling system and the cooling fluid is also flowed through thesecond cooling emitter, wherein the cooling fluid is heated, while beingflowed through the second cooling emitter.
 8. The method according toclaim 6, wherein the method comprises providing air conditioning for afacility and that the method further comprises blowing the first airflow from the first ventilation system, with a supply air fan, into afirst area of the facility, the second air flow is drawn into the secondventilation system from a second area of the facility, which can beoverlapping with the first area, and the second air flow is blown fromthe second ventilation system into a third area of the facility, whichcan be overlapping with the first and/or the second area.
 9. The methodaccording to claim 8, wherein the method further comprises measuring anoutside air temperature, the temperature of a first cooling fluid and/ora second cooling fluid and/or an ambient temperature in the first,second and/or third area of the facility, and controlling a flow of thefirst air flow, and/or of the second air flow, controlling the flow ofthe cooling fluid, controlling the flow of a heating fluid in theheating system, and/or controlling the power of the cooler and/or theheater.
 10. The method according to claim 1, wherein the method furthercomprises filtering the first air flow in the first ventilation system,and humidifying the first air flow in the first ventilation system witha humidifier.
 11. A device for conditioning air, comprising a firstventilation system with a first air flow, the first ventilation systemcomprising a first air intake, a first output or air supply, and a firstcooling coil therebetween, wherein the first cooling coil is connectedto a cooling system with a cooler, a second ventilation system with asecond air intake, a second output or air supply, and a second coolingcoil therebetween, the second ventilation system with a second air flow,within which the second cooling coil is arranged wherein the secondcooling coil is connected to the cooling system, wherein the coolingsystem comprises a controller configured to conduct the method accordingto claim
 1. 12. The method of claim 2, wherein the outside air is drawnin through an air intake damper.
 13. The method of claim 9, wherein theflow of the first air flow and/or of the second air flow is controlledby regulating the supply air fan and/or an air intake damper.
 14. Themethod of claim 9, wherein the flow of the cooling fluid is controlledby using and regulating a valve and/or a pump in the cooling system. 15.The method of claim 9, wherein the flow of a heating fluid in a heatingsystem is controlled by using and regulating a valve and/or a pump inthe heating system
 16. The method of claim 10, wherein the first airflow is filtered by panel filters and/or bag filters.
 17. The device ofclaim 11, wherein the first ventilation system and/or the secondventilation system is connected with the outside.
 18. The device ofclaim 11, wherein the first ventilation system and/or the secondventilation system comprises an air intake damper.
 19. The device ofclaim 11, wherein the first ventilation system further comprises a firstheating coil, which is connected to a heating system with a heater. 20.The device of claim 19, wherein the controller is configured to conductthe method according to claim 3.